"What are you doing here?" the consul general asked the man who was fast becoming one of the most famous faces in the world. "Well, I'm retired, so I have to get my paper that I'm still alive," said Blix, apparently oblivious to the fact that he was by now the owner of one of the most famous names on the planet.

The very idea that Blix, the man the world had charged with the responsibility of adjudicating between war and peace, felt the need to confirm his earthly existence tells us a great deal about the characteristics that have guided him in recent times.

Formal, self-deprecating, proper and precise, Blix has spent the last few months buffeted by the transatlantic diplomatic storms and emerged with the few hairs he has left on his head in place. Not for him an emotional response to the horrors of war that he believes, at least for now, could have been avoided. Offer him a range of adjectives to describe his mood at the breakdown of talks - even as he argued that further inspections could still produce results - and he picks only "sadness" and "disappointment", not "anger" and "frustration".

"Sadness because now it was a matter of using force and destruction," he says. "Disappointment because I thought it was too early breaking off the attempts to achieve disarmament. I thought there should have been a little more patience."

But time was one thing the Americans would not give him. "From the end of January, beginning of February the Americans were losing patience," he says. "Even though I was reporting on some improvements and some positive features, I think that they were moving towards the other conclusion."

With the British and Americans insistent that Iraq had weapons of mass destruction, even if they didn't know where they were, Blix felt that there was little he could do to prove otherwise. "The big difference between us and the UK and US was that all the intelligence agencies were convinced that there were weapons of mass destruction, whereas I had not seen evidence.

"We would say, 'Iraq should present any anthrax', while the US and UK were inclined to say, 'Iraq should present the anthrax.' "

Such was Blix's dilemma. Every few weeks this mild-mannered, even-tempered Swede would take centre stage as the honest broker in an increasingly ill-tempered and divided debate. A civil servant in a chamber of entrenched partisans. When called to the table, he would emerge, plodding purposefully towards his seat. A small, tubby man with grey hair and a grey suit - a shade of grey in a room full of black and white.

Diplomats, soldiers, Iraqi civilians and national governments hung on his every word seeking to discern some nuance, inflection, emphasis or denial that might presage an uncertain future. Markets fell and rose on his every word. The Americans and the French would seize on various aspects to justify their positions. And throughout it, Blix maintains, he tried to keep his eyes on the prize. "We saw our job all the time as a technical, independent and impartial work that was taking place in a political minefield," says. "People would say, 'You were playing into the hands of the hawks,' and I would say, 'We aren't playing at all.' "

And yet, for all his attempts at denial and avoidance, from the outset Blix has often become the issue. The Americans were not keen on his appointment as head of the UN monitoring, verification and inspection commission. They expressed doubts about the quality of his work after he concluded, during the 80s, that Iraq was not trying to build a nuclear weapon. But when inspectors went in after the Gulf war, they found an aggressive nuclear weapons programme in place, and Saddam only around six months away from acquiring a bomb.

"It's correct to say that the International Atomic Energy Agency was fooled by the Iraqis," he says. Leading hawk and deputy US defence secretary Paul Wolfowitz even got the CIA to investigate him - a fact that makes Blix laugh. "That wasn't serious. Everything they wanted to know they could have got from the state department."

Only a few weeks ago the Americans accused him of hiding information that would have been helpful to their case regarding drones and cluster bombs. Here Blix comes the closest he probably gets to being angry. "This was advanced as an argument against us as a battle for votes. But I think it was unfair, unjustified sniping."

If his trip to the Swedish embassy tells us something about his character, then his favourite phrase when navigating these byzantine negotiations is informative about his philosophy. "The noble art of losing face," he says, "will one day save the human race."

Yet despite the fact that there was little nobility displayed in the negotiations and that large numbers of the human race are perishing through military action despite his efforts, he does not regret picking up the phone to Kofi Annan four years ago while on an Antarctic cruise with his wife, and coming out of retirement to take on the job. "I was taken out of the refrigerator, literally," he said recently. "I have my career behind me."

The life ahead of him appears somewhat solitary. He lives in New York, his wife is in Sweden. At 74, he confesses to living the life of a "monk". His only indulgences are bordeaux and oriental carpets; his main hobbies, preparing Scandinavian fish dishes and making his own marmalade. This is a man who spends his leisure time reading political biographies and UN documents.

His office, on the 31st floor of the United Nations, with a striking view of the Chrysler building, is decorated with aerial pictures of Baghdad. "A lot of these buildings have probably been bombed now," says his press spokesman, dashing his pen across vast swathes of the city, pointing out the government ministries.

Blix believes there was nothing he could have said that would have convinced the Americans not to go to war at this time. "They would have wanted a clear-cut guarantee that [the Iraqis] did not have weapons of mass destruction," he says. "I could not have given them a guarantee that if they had waited a few months more there would have been results."

Could anyone have given them a guarantee?

"Not at this stage. Now we'll see if occupation does it. If we had come out and said on the basis of what we had and said, 'We can solve this in three months,' they would have said, 'You're not credible.' "

So what was the point of it all, then? Of all the shuttling backwards and forwards, the weighing of words and the delivering of reports when so soon after his first report war seemed inevitable?

Blix's response is a masterpiece of the diplomatic understatement for which over a few short months he became a byword: "While we were disappointed that it didn't continue and that it came to war, I think we have shown that it was feasible to build up a professional and effective and independent inspection regime... it's just too bad it didn't work."

The Blix file

· Born 1928 in Uppsala, Sweden.

· Studied at the University of Uppsala; at Columbia University; and at Cambridge University, where he received his PhD.

· Appointed Swedish minister for foreign affairs in October 1978.

· From 1961 to 1981, he was a member of Sweden's delegation to the UN General Assembly.

· Served as director-general of the International Atomic Energy Agency for 16 years until 1997, directing the response to the Chernobyl disaster.

· Appointed executive chairman, UN monitoring, verification and inspection commission (UNMOVIC), by the UN secretary-general in January 2000. By Amy Fleming